Drivers of large trucks, particularly trucks with trailers, such as the eighteen wheel vehicles used to transport goods over highways, have their vision partially blocked by the body or trailer of the vehicle. To provide for the orderly flow of traffic, trucks typically use the right hand lane of the road except when passing or turning. When a large truck passes another vehicle, the driver tries to return to the right hand lane as quickly as possible. Doing so keeps the driver aware of his surroundings because it minimizes the possibility that a vehicle can approach from the rear in the right hand lane in a blind spot of the truck driver thereby creating a hazardous condition.
A courteous driver will flash his headlights momentarily or switch from low beam to high beam to alert the truck driver that it is safe for the truck to return to the right hand lane. As a return courtesy, the driver of the truck will flash the trailer lights as a thank you for the driver giving the indication that it is safe to return to the right hand lane. The truck driver will typically operate a switch that causes the truck lights to flash momentarily.
Unfortunately, in many instances, flashing the trailer lights of a tractor-trailer also interrupts the circuit to the head lamps causing the headlights flash also. This flashing of the headlights can be annoying to oncoming vehicles and can cause the headlights to fail prematurely. Also, flashing the lights can cause a momentary power surge which decreases the useful life of the truck lights and can damage internal components of the vehicle electrical system. Accordingly, it will be appreciated that it would be highly desirable to acknowledge courteous drivers without subjecting the electrical system of the vehicle to damage and without causing premature failure of the lamps.
Some tractor trailers are equipped with tail lights on the trailer portion of the vehicle that can be operated by a switch by the driver to cause the tail lights to flash without engaging other lights in the electrical system. These lights work well at night and are highly visible at night, however, they are not as effective in day light. It is desirable to have a lighting system that is effective in day light as well as at night, and does not interfere with the remainder of the electrical system of the vehicle.
Another problem with lights on the trailer portion of the vehicle is that the lights are on the perimeter of the rear end of the trailer far above the eye level of drivers of passenger cars. Accordingly, it will be appreciated that it would be highly desirable to have a courtesy light that is near the eye level of drivers of passenger cars so that the courtesy light is more noticeable.